A flotation device of the above-mentioned type is known from—inter alia—U.S. Pat. No. 6,974,357 (Van Mil et al.). The teachings thereof are incorporated herein by reference.
In one embodiment, the known flotation device is provided with means for attaching the flotation device to a pair of spectacles that is to be retrieved, with a spray water-resistant holder that comprises a mechanism for opening the holder, which holder in its closed state encompasses an empty, inflatable body of a substantially water-permeable and air-impervious material in a folded state. The inflatable body in its uninflated state is sealed off from the rest of the interior of the holder by means of a seal comprising a water-permeable substance. The material of the inflatable body itself also comprises a water-permeable substance. The inflatable body further comprises within it one or more reagents which react under the influence of water that ingresses in the holder to form a gas, which gas serves for inflating the folded inflatable body in order to exert a flotation force on the pair of spectacles to which the flotation device of the invention is attached. In action, when an object to which the known flotation device is attached, is dropped in water, water permeates through the surface of the inflatable body. After enough water has been taken up by the material of the inflatable body, the pores of the material close and thus become substantially waterproof and impervious in regard of gas that forms as a result of the reaction of the reagents under the influence of the water within the inflatable body.
It is an object of the invention to provide for an improved flotation device of the type described in the pre-amble that is more compact and lightweight than the known flotation device.
It is also an object of the invention to provide for an improved flotation device which in action can be inflated very rapidly.
It is still another object of the invention to provide for an improved flotation device which can exert a large flotation force that is sufficient for floating large and heavy objects.
It is further another object to provide for an improved flotation device which in its un-inflated state can retain its potential working during a long period of time.
It is further yet another object to provide for an improved flotation device which in its inflated state can maintain the flotation force exerted by it during a long period of time.
It is also an object of the invention to provide for an improved flotation device which is more cost-effective to manufacture than the known flotation device.
It is also an object of the invention to provide for an improved flotation device which is more reliable in use than the known flotation device.